We've been working on a number of bugs. A good number of them came from the new markup implementation. It touched almost every corner of the site. Although the old implementation was janky, the content jived with it. The new implementation is more robust, but edge cases have been popping up here and there.
You should be seeing less of the 502 in the coming weeks. However, if you do find a bug that sends you to one. Let us know. You probably aren't the only one that has experienced it.